Nick Taylors blog

I’m happy that I’ve managed to get my Icom IC-2820 radio and Kenwood RC-D710 TNC/data terminal to work together so I can now use the “left side” of the 2820 for APRS on 144.39 MHz and use the “right side” for D-STAR and conventional voice communications. This configuration passes GPS data from the GPS in the IC-2820 to the RC-D710 which in turn sends back APRS data which is transmitted by the 2820. I’ve also upgraded the GPS antenna to a waterproof active antenna from Gilsson (#MCX180) which has a straight through MCX connector and fits, with a little trimming.

To do this, you’ll need the following (if you’re not making your own cables):

• Icom IC-2820 D-STAR radio
• Kenwood RC-D710 TNC/data terminal/control panel
• Kenwood PG-5J interface kit for RC-D710
• Kenwood PG-5G programming cable (to connect to a PC running Windows)
• Kenwood MCP-2A, “Memory Control Program” software (a free download)
• A PC running Windows for the MCP-2A software
• 6-pin mini-DIN cable that comes with the PG-5J
• A data cable with 2 mini-stereo jack plugs (the RC-D710 came with such a cable, but with only one jack plug)

After the usual preparation (checking items, installing powerpole connectors on the power cable, etc.) I powered off the radio and TNC, and connected the 6-pin mini-DIN cable from the main unit of the 2820 to the “data” socket on the PG-5J interface unit. I then connected the RJ-45 cable between the PG-5J and the RC-D710 panel. Finally, I had to connect the mini-stereo jack cable from the RC-D710 panel to the main unit of the 2820. I assumed that there would be a mini-jack at each end of the cable, but, no! Fortunately, I had two of these cables and I chose to connect them together. It’s a very small cable, with what seems like 3 strands of very thin copper in 3 cores (it’s a stereo cable). My soldering ability wasn’t up to the job, so I gave up and used a terminal block, which works nicely for testing (I’ve ordered a 10ft ready-made cable from Monoprice).

Next, I connected the RC-D710 to my PC and upgraded the firmware (it was v1.x and v2.01 is current), and then used the MCP-2A software to read the default config. This software is the only way to change the configuration elements on the RC-D710. I upped the levels as described in this article, viewed the other configuration items and set my callsign info, as well as some custom messages, setup smartbeaconing, etc. and on the IC_2820 I made sure in the data function that “G-D” was on (this sends GPS data via the stereo data cable to the D710), and in the menus (GPS sentence) I set RMA and GGA to on. In the packet menu, I set the packet operation band to “left” so the APRS data will only transmit on the band I have set to 144.39 MHz.

I feel I’ve only just scratched the surface, and will experiment a little more to optimize the configuration, but my first impression is that this will prove to be a great setup.

For years I’ve used the Garmin GPSMAP 478, it’s got me across the Rub ‘al Khali, seen service in the Sahara and been all over the USA. It’s a fantastic piece of equipment, rugged, robust and reliable. I’ve not had a single problem with it in the last 3 or 4 years. It’ll do turn-by-turn navigation and chart-plotting – an essential feature not just for mariners, but also for those of us who explore the more remote parts of the world. The 478 has served me well and I have no hesitation in recommending it highly. I only had two minor criticisms - it’s be nice to have a slightly larger screen and let’s stop using the proprietary Garmin Data Cards. 

Well, there’s a new kid in town. The Garmin GPSMAP 640 looks like it’s going to be the new favorite of overlanders. It addresses both of my issues with the 478. It takes SD cards, and the display is a 13.2 cm (diagonal) with a resolution of 800×480 WVGA (the 478 is 9.4cm on the diagonal and has a resolution of 480×320). It’ll calculate faster than the GPSMAP 478, with SD cards it can support more memory, but it is a bit bulkier (15.0 x 10.2 x 4.8 cm vs the 478 at 14.5 x 8.1 x 4.8 cm). 

There is also a GPSMAP 620, which is physically the same at the 640, but doesn’t support the XM Radio and XM Weather (which I use frequently, very handy having radar overlays when you’re in the mountains in the summer), and doesn’t come with any maps preloaded. It also costs $200 less at MSRP. 

For XM Radio and XM Weather, you’ll need the new GXM40 antenna (with the very odd MSRP of 267.84). It seems the old GXM30 won’t work with the 640, and you’ll have to transfer your existing XM subscription to the new antenna. 

The GPSMAP 640 isn’t available until Q1 2009, with an MRSP of $1199 (but already available for pre-order from around $950).

As soon as Ram Mounts have their brackets ready, I’ll get one ordered.

Continuing my project to have at lease least a dual-band 2m/70cm radio in the vehicles we use to travel to remote places, I got around to installing the Kenwood TM-D710 into the Dodge Ram. A few weeks ago, I read a review of the Green Light Labs GPS-710, a compact GPS that can attach to the rear of the D710s control panel. I installed that, too.

The Kenwood TM-D710 is a great radio. I didn’t think there’d be much improved over the TM-D700 (which I also own), but I like the new software and interface, it’s a little more logical to use.

The Green Light Labs GPS-710 is a very compact and sensitive (20 channel SiRF-III chipset) GPS unit. It simply attached attaches to the rear of the D710 control panel with strong adhesive strips. A small jumper cable connects it to the panel for power, and another small lead delivers the NMEA output. After it was connected, there are just a couple of settings to change in the radio and It Just Works.

Installing the radio was also quite easy. There were already some hold holes in the transmission tunnel console, where I suppose a radio was previously mounted. I reused most of the holes, and found some good stainless steel hardware to use with the supplied bracket.

Next, running the power and antenna cables was quite easy. There’s a bulkhead hole, complete with rubber weatherproofing above the clutch pedal. I simply ran the cables (and props to Diamond antenna who provide small plugs on their cables just for this purpose) through the bulkhead hole and cable-tied them above the pedals and ran them into position. The cables simply pushed up into the console, but I cable-tied them inside to keep them secure.

Next I mounted the control panel on the dash, using the supplied bracket and adhesive stand. It seems to be sticking well enough as I write this.

Finally, I had to run the control cable from the radio, being behind the glove box and up onto the dash. The Dodge Ram has a reasonable easy way to do this on the passenger side, it’s a bit busy on the drivers side, but Kenwood provide a long cable so the passenger side worked well. This cable is completely hidden except from the glass to the radio, which is about all you could hope for unless you drill the dash.

Finally, I tidied things up and gave it a test. Worked first time!

KD0AIC-12 is on the air!

I’ve finally installed Mobile APRS in the Green D90. I’ve had static APRS working, but it was time to integrate GPS into the system; particularly useful when we head out to remote locations as we do most weekends.

The original plan was to simply send the trucks current coordinates as acquired by the GPS via a TNC to the radio and out, to be picked up by other stations and relayed to an igate and from there onto the internet where many various sites show your position in near real-time.

This would have been a very simple setup consisting of a Garmin GPS16HVS, an OEM unit that basically integrates the GPS and antenna into a single unit without a display, a Kantronics MT-1200 TNC and an Icom IC-2200 single band radio.

However, I ran out of time (I wanted it working for our Utah “Hole in the Rock” trip), and didn’t want to go back to Radio Shack for another 2.5mm 3 way jack so I dug out my “spare” Kenwood TM-D700A, which has a built it TNC and would save some time during the configuration.

With the Kenwood radio, the system simply consisted of the GPS16 connected to the D700A radio.

Installing the GPS16 was a small problem. It comes with a magnetic mount, which, of course, is no use in an aluminum-bodied Land Rover Defender (actually, it’s Birmabright). The green D90 is a bit old and beat up anyway, so I wasn’t too bothered about drilling the roof. I drilled 4 holes for the GPS16 and another 4 for the cable passthrough (a waterproof marine-grade “Cable Clam“, made by Blue Sea Systems and available from from West Marine), and simply fed the cable through.

The GPS16 ships with an RJ45 connector, and I can’t imagine what use it has except for factory testing. After cutting it off, there are basically 2 sets of data wiring and also power wires in a very compact space (as described in the manual – PDF link). It’s a simple job, but fiddly connecting the power to my usual 45A Anderson Powerpole connectors and a 3-way 2.5mm jack. Initially I forgot that the data ground has to be cross connected to the ground, so the GPS did not switch on.

I removed the 2.5mm jack and connected an DB9 socket so I could connect a terminal to the GPS16. It was about now I realized that it wasn’t powered on (there is no indicator light to show this), but I was amising myself watching the NMEA sentences appear on my terminal. I also downloaded the Garmin SNSRCFG software, which enabled me to play with a ton of settings in the GPS16. I just made sure the data it was acquiring was correct before disconnecting it and putting the 2.5mm jack back on.

Then, I connected the jack to the radio and to my delight I saw the GPS indicator flashing, meaning that the radio was receiving telemetry from the GPS. Fiddling with a few settings on the radio, to configure it to take position data from the GPS and override the manual co-ordinates I’d entered earlier, I saw the “MY POS” indicator flash up, showing that APRS data was being transmitted. A drive around the block and a quick visit to db0anf, and I could see my position being updated in near real time. Success!

You can see my position updates here.

Overall, the Garmin GPS16 and Kenwood TM-D700A radio is a great combination for hands off APRS work.

I do have a few more steps to finish this little project, including making a small breakout box for the GPS16, which will have switched power and a connection for both the radio (via a jack) and terminal (via a DB9). And then I’ll have to do it all again for the black D90!

There’s a turn near our house (E 9th Ave 7 and Colorado Blvd), that all my GPS’s get wrong. I was pleased to see that NAVTEQ (who supply many vendors with mapping data) have an easy way to submit corrections. It’s called Mapreporter, and it’s a pleasure to use.